func NoteOff(stream *portmidi.Stream, note int64, velocity int64) {
stream.WriteShort(0x80|(midiChan-1), note, velocity)
playing = -1
}
func AllNotesOff(stream *portmidi.Stream) {
stream.WriteShort(0xB0|(midiChan-1), 0x7B, 0x00)
playing = -1
}
func NoteOn(stream *portmidi.Stream, note int64, velocity int64) {
playing = note
stream.WriteShort(0x90|(midiChan-1), note, velocity)
}